This invention relates to a caulking gun having a built-in cutter for cutting the tip off the spout of a caulking cartridge.
Caulking gun is a device to squeeze caulking material inside a caulking cartridge out of a funnel-like plastic spout of the caulking gun or the caulking cartridge. Caulking guns could be classified into two types. The first type is those caulking guns that have caulking function but without a built-in cutter for cutting off a tip of the funnel-like plastic spout. A user has to find a knife or a scissors to cut the spout tip off before caulking, such as U.S. Pat. No. 3,069,053 to Nelson, U.S. Pat. No. 4,461,407 to Finnegan and U.S. Pat. No. 5,615,807 to me. The second type is a caulking gun having caulking function and a built-in cutter for cutting off the tip of the plastic spout. There are several designs of caulking guns with built-in cutters for cutting the tips off, for example, U.S. Pat. No. 3,189,226 to Sherbondy, U.S. Pat. No. 4,135,644 to Pacetti, U.S. Pat. No. 4,390,115 to Bigham and U.S. Pat. No. 4,493,437 to Breeden.
The caulking gun with built-in cutter lets a user more convenient to do caulking job. However, all prior designs of caulking gun with built-in cutter have at least the following disadvantages:
(a) There are two types of frame-handle structure for all caulking guns. One structure has a U-shape cross section of handle made of stamped steel sheet, such as U.S. Pat. No. 2,786,603 to Collins. Another structure has a non-U-shape cross section of handle manufactured by die casting, plastic injection or other methods, such as the caulking gun shown in U.S. Pat. No. 5,156,305 to Eyre. Ether caulking guns with U-shape handle or with Non-U-shape handle are widely used in caulking jobs. Any of built-in spout cutters of prior arts can be built in only a caulking gun with a U-shape handle, but not a caulking gun with a Non-U-shape handle. Not just because these built-in cutters of prior art are all designed for building in the caulking guns with U-shape handle, but also because the U-shape handle provides a cover for the sharp cutting edge for finger protection of a caulking gun user.
(b) The principles of spout cutting of all built-in cutters of prior art are scissors-like function. However, it is difficult to manufacture a built-in cutter of a caulking gun as a good function of scissors. Those unperfected scissors-like cutters are hard to cut off the spout tip completely. Even a spout tip is cut off by the scissors-like cutter, however, the spout opening does not have a desirable shape for doing a nice caulking job in many cases.
(c) The cutting operation is not smooth and needs big force when those unperfected scissors-like cutters are used.
(d) Those spout cutters can not be convenient for both right-hand users and left-hand users because a cutter can be formed on only one side of a caulking gun.